If you are going to be racing how important is a one way diff? Does it help a lot?

They do help, but if you are a beginer you probably wouldnt even notce the difference and you would pobably do better without a One way.

A one way helps you get more speed in the corners, but it limits the amount of brake you can use. With front one-way you have to tune your brakes way way down, and you can only use the brake for a slip second, while your going perfectly straight, or else your car will spin out. Thats why drivers with a one way barely even use the brake during a whole race.

How does using a reciever with anti-lock brakes effect the one-way? since it is pulsing the brakes, would I be able to use the more to help with speed entering corners?

I dont think that would help, it is definently not necesery to have a front one-way to race. I started racing with an RS4 and i was able to get preatty good laptimes. The best laptime at my trakc ever was 16.96. and during most A-main races the fastes lap time was around 17.5 After a year and a half i could run a 19.5 laptime with my RS4 and 90% of the people in the a-main were pro's because this was the only track in Miami i there were alot of Pro's from Miami.

becareful using that pulsating feature on analog servos it can cause them to overheat very quickly, only use it with digital servos

the abs feature is really only useful for off road racing where there is less traction and more tire slippage

too much brakes only lowers your lap times, try letting off the throttle sooner and alter your lines into the turns